ANTICONVULSANTS

ANTICONVULSANTS:

Q. A 35-year-old woman, recently diagnosed with simple partial seizures, started the prescribed therapy. Her past history was unremarkable, but her mother was known to suffer from acute intermit tent porphyria. Which of the following anticonvulsant drugs would be appropriate for this patient?
A. Diazepam
B. Ethosu ximide
C. Valproic acid
D. Carbamazepine
E. Phenytoin
F. Lamotrigine

Ans:  F.  Lamotrigine

Explanation:  Lamotrigine is effective in simple partial seizures, as well as in generalized tonic-clonic and absence seizures. It appears to have comparable effectiveness with more traditional anticonvulsant drugs, such as valproic acid, carbamazepine, and phenytoin. The primary mechanism of action of lamotrigine most likely includes a frequency-dependent blockade of voltage-gated Na+ channels. C−E Valproic acid, carbamazepine, and phenytoin are firstchoice drugs in partial seizures, but they are contraindicated when there is a risk of acute intermittent porphyria, because they can trigger an attack. Because acute intermittent porphyria is an autosomal disorder, it is bet ter to avoid these drugs in patients whose parents are known to suffer from the disease, as in this case. A, B Diazepam and ethosuximide are not effective in simple partial seizures.

Q. A 53-year-old man suffering from partial seizures had been receiving a high dose of carbamazepine for 6 months. Which of the following dose-related adverse effects most likely occurred during the therapy?
A. Gingival hyperplasia
B. Hallucinat ions
C. Ataxia
D. Stevens−Johnson syndrome
E. Heart failure
F. Dilut ional hyponatremia

Ans: C. Ataxia

Explanation: Some of the adverse e ects of carbamazepine are related to cerebellar-vestibular impairment. The most common  dose-related adverse effect of this kind is ataxia (up to 15%

of patients). A This would be an adverse e ect of phenytoin. It does not occur with carbamazepine. B, D−F All these are serious but quite rare adverse effects of carbamazepine.

 
Q. A 24-year-old woman with a long history of absence seizures had been successfully managed with valproic acid for the past 5 years. The patient had recently married, and during her last visit she expressed the desire to start a family. Which of the following drugs would be most appropriate for this patient to substitute for valproic acid therapy?
A. Carbamazepine
B. Clonazepam
C. Phenytoin
D. Ethosuximide
E. Phenobarbital
F. Tiagabine

Ans: D. Ethosuximide

Explanation: Valproic acid is classified by the U.S. Food and Drug Administration as pregnancy category D because it increases the 
 risk of neural tube defects (up to 20-fold) when given during pregnancy. Ethosuximide is instead classi ed as pregnancy category C and is a rst-line drug for absence seizures. A−C, E, F These drugs are not effective (and some of them can even be dangerous) in absence seizures.